Biomass, such as forestry and agricultural products and residues, is a major underutilized product in the world. The U.S. Department of Energy estimated that there are over 12 million dry tons of biomass residues generated each year in Georgia that could be used for energy and chemical production. There are several different technologies for converting the biomass to useful energy (e.g., direct burn, co-firing, gasification, and the like) or to biobased products (e.g., fermentation, pyrolysis, and the like), in particular bio-oil. Depending on the type of process used, the final product may have different values and applications. In most cases these products replace those generated from crude oil, thus having long-term sustainability and environmental benefits (e.g., being carbon neutral).
The use of biomass pyrolysis derived bio-oil as a diesel fuel extender or substitute has long been a goal of the biofuels research community. Bio-oil is a mixture of water, light volatiles, and non-volatiles and is highly reactive because of the presence of significant quantities of oxygen. The diversity of chemical species within bio-oil is derived from the decomposition of cellulose, fatty acids, triglycerides, lignin and hemicellulose polymers, the major components of biomass. Aside from water, a major component of these oils, they also contain over 300 identified compounds including hydroxyaldehydes, hydroxyketones, sugars, carboxylic acids, furans and phenolic compounds. Bio-oil also contains several phases due to the different physical states of the chemical components. The exact chemical makeup of bio-oil is determined by several factors such as feedstock, pyrolysis temperature, pyrolysis method and speed of pyrolysis.
The reactivity of functional groups and high water content of this oil results in its immiscibility with petroleum based diesel fuel. One common method for addressing this issue has been development of emulsions of diesel fuel and bio-oil. However, the high cost of forming and maintaining these emulsions is an obstacle to their economic feasibility. Additionally, these emulsions are limited to 30% bio-oil with petroleum diesel.